Communicating media content from a DVR to a portable device

ABSTRACT

In a method for communicating media content stored on a digital video recorder (DVR) protected by a first DRM system to a portable multimedia device (PMD) using a second DRM system, in which the first DRM system differs from the second DRM system, a request for communication of a media content item stored on the DVR to the PMD is received. In addition, a portable content key is employed to encrypt the media content item to a PMD format suitable content version and the encrypted PMD format suitable content version is communicated to the PMD along with a portable content identifier (ID).

CLAIM OF PRIORITY

The present application claims the benefit of priority to U.S.Provisional Patent Application Ser. No. 61/053,929, filed on May 16,2008, entitled “Method to Obtain Content Keys to Enable Transcoding”,the disclosure of which is hereby incorporated by reference in itsentirety.

BACKGROUND

There has been substantial growth in the use of set-top boxes (STBs)equipped with digital video recording capabilities. Users often recordcontent, such as, television programs, onto the digital video recorder(DVR), which is often referred to as a personal video recorder (PVR).The users are then able to view the recorded content at a later time ona monitor to which the DVR is connected. Oftentimes, however, userswould like to copy the recorded content onto a portable multimediadevice (PMD) or a portable media player (PMP), such as, a laptopcomputer, a personal digital assistant (PDA), and a cellular telephone.

Directly copying of the content recorded on the DVR onto the PMDs isoften limited by a number of factors. One of these factors is that theformat in which the content is recorded onto the DVR is typicallyincompatible with the playback formats of the PMDs and thus, even if thePMDs are able to store the content recorded on the DVR, the PMDs aretypically incapable of playing the content. Another factor is that thePMDs are often equipped with a different digital rights management (DRM)system than the DRM system that manages digital rights of media contentstored and played on the DVR. The DRM systems typically preventunauthorized copying of content onto and playback of the content on thePMDs.

SUMMARY

Disclosed herein is a method for communicating media content stored on adigital video recorder (DVR) protected by a first digital rightsmanagement (DRM) system to a portable multimedia device (PMD) using asecond DRM system, in which the first DRM system differs from the secondDRM system. It is assumed that the DRM used by the PMD is typically usedto get a content decryption key, for instance, in the form of a license,from a license server, but the PMD may not know how to get the contentdecryption key from the DVR. In the method, a request for communicationof the media content stored on the DVR to the PMD is received. Inaddition, a portable content key is employed to encrypt the content to aformat suitable for the PMD and the encrypted PMD format suitablecontent version to the PMD is communicated to the PMD along with aportable content identifier (or portable content ID).

Also disclosed is a rights manager for managing rights to media contentfrom a first digital rights management (DRM) format suitable for adigital video recorder (DVR) to a second DRM format suitable for aportable multimedia device (PMD). The rights manager includes a modulefor receiving a media content identification (ID) of the media contentstored on the DVR, a module for encrypting a PMD format suitable contentversion of a media content item using a portable content key, and amodule for communicating the encrypted PMD format suitable contentversion to the PMD.

Also disclosed is a method for communicating a content key from the DVRto the license server. This is useful when the content on the DVR doesnot have to be transcoded and re-encrypted with a new content key forthe media content to be received and played back in a PMD. In thismethod, the content key that protects the content stored on the DVR iscommunicated to the license server such that the PMD may rely upon thecommunication channel used by the DVR to request a content key from thelicense server to receive the content key. This allows the DRM system onthe PMD to work without modifications or integration with the DRM systemon the DVR.

Further disclosed is a computer readable storage medium on which isembedded one or more computer programs, the one or more computerprograms implementing a method for communicating media content stored ona digital video recorder (DVR) protected by a first DRM system to aportable multimedia device (PMD) using a second DRM system, wherein thefirst DRM system differs from said second DRM system. The one or morecomputer programs include a set of instructions for (a) receiving arequest for communication of a media content item stored on the DVR tothe PMD; (b) employing a portable content key to encrypt the mediacontent item to a PMD format suitable content version; and (c)communicating the encrypted PMD format suitable content version to thePMD along with a portable content identifier (ID).

Commercial content on PMDs is often protected by one or more DRMsystems, which substantially restrict the copy and playback of mediacontent on the PMDs. Thus, PMDs are typically unable to readily playbackmedia content originally copied from another device, such as, a DVR.Through implementation of the embodiments disclosed in the presentinvention, media content stored on a DVR may be readily copied andaccessed on a PMD, while complying with the one or more DRM systems thatprotect content on the PMD.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments are illustrated by way of example and not limited in thefollowing figure(s), in which like numerals indicate like elements, inwhich:

FIG. 1 illustrates a block diagram of a content sharing system,according to an embodiment;

FIGS. 2A and 2B, respectively, illustrate flow diagrams of methods forcommunicating media content stored on a digital video recorder (DVR) toa digital rights management protected portable multimedia device,according to two embodiments;

FIG. 3 illustrates a flow diagram of a method of generating andcommunicating a content key, according to an embodiment;

FIG. 4 illustrates a flow diagram of a method of enabling media contentfrom the DVR to be accessed in the PMD, according to an embodiment;

FIG. 5 illustrates a method of generating and communicating a portablecontent key, according to an embodiment; and

FIG. 6 shows a block diagram of a computing apparatus configured toimplement or execute one or more of the methods depicted in FIGS. 2A-5.

DETAILED DESCRIPTION

For simplicity and illustrative purposes, the principles of theembodiments are described by referring mainly to examples thereof. Inthe following description, numerous specific details are set forth inorder to provide a thorough understanding of the embodiments. It will beapparent however, to one of ordinary skill in the art, that theembodiments may be practiced without limitation to these specificdetails. In other instances, well known methods and structures have notbeen described in detail so as not to unnecessarily obscure theembodiments.

For purposes of the present disclosure, it is assumed that the portablemultimedia device PMD or portable media player (PMP), which arediscussed interchangeably herein, is equipped with an existing, possiblystandardized, digital rights management (DRM) system that cannot beeasily modified or extended. Examples of suitable DRM systems include,for instance, WMDRM-PD, OMA DRM v2, Marlin, etc. These DRM systemstypically identify protected content, use a content ID (or a content keyID) to request the content key and associated DRM rights from a licenseserver. The license server or a Rights Issuer typically deliver the keyand the rights in the form of a License or a Rights Object. Such DRMsystems cannot be easily used to obtain content that does not originatefrom the service provider's content server, such as, from a digitalvideo recorder (DVR) or a personal video recorder (PVR), which are alsodiscussed interchangeably herein, in the user's home.

Disclosed herein is a method for translating the digital rights for themedia content stored on a DVR to a PMD. More particularly, the rightsare translated to enable the media content to be accessed and played ona PMD that is protected by one or more DRM systems. The DVR content maybe converted to a format more suitable for playback on a PMD, forinstance, it may be transcoded to another video or audio format,different file format, and transcrypted (re-encrypted) using a differentcontent key or a different encryption algorithm.

As used herein, the term “content identification (ID)” generally refersto a substantially unique identification value assigned to media contentitems stored on the DVR. In the context of a DRM system, it is typicallyused to identify the associated content key.

The term “content key” generally refers to a content encryption keysuitable for protection (or encryption) of media content during itstransfer from the source (e.g., a content server or a DVR) to adestination client device such, as a PMD, and for protection of themedia content while it is stored on the DVR or on the PMD. The same keymay be used to decrypt the content while it is played back on the clientdevice. A content key is typically associated with a set of rights orrestrictions that the DRM system employed by the device checks beforeDRM system allows the content to be decrypted and played back on thedevice.

The term “DVR content key” here refers to a content key used by the DRMsystem on the DVR to protect, such as, by decrypting and/or encrypting,the content stored on the DVR.

The term “portable content key” here refers to a content key suitablefor decrypting and/or encrypting the media content copied to and storedon the PMD. Unless otherwise specified, the term “content key” in thisdisclosure refers to the “portable content key”.

With reference first to FIG. 1, there is shown a block diagram of acontent sharing system 100, according to an example. It should beunderstood that the following description of the content sharing system100 is but one manner of a variety of different manners in which such acontent sharing system 100 may be configured and operated. In addition,it should be understood that the content sharing system 100 may includeadditional components and that some of the components described may beremoved and/or modified without departing from a scope of the contentsharing system 100.

The content sharing system 100 is depicted as including a digital videorecorder (DVR) 102, which is also often referred to as a personal videorecorder (PVR). The DVR 102 is generally configured to operate as aset-top box (STB) and is thus operable to be connected to a contentprovider, such as, a cable service provider, a satellite serviceprovider, IPTV provider, etc., through a communications network 110. Thecommunications network 110 may, for instance, include a broadbandconnection to the content provider, such as, over optical fiber, hybridfiber coaxial cable network, satellite signals, terrestrial signals,etc. The communications network 110 may also include a cable modem, anintegrated services digital network modem, a digital subscriber linemodem, etc., that enables the DVR 102 to communicate to the contentprovider over the communications network 110.

In any regard, the DVR 102 receives media content, such as, networktelevision programs, pay-per-view movies, pay-per-view events, video ondemand, video file downloads, etc., from the content provider throughthe communications network 110. The media content is typically encryptedand protected using a digital rights management (DRM) system. Moreparticularly, the media content is often encrypted and the DVR 102typically includes hardware and/or software configured to decrypt theencrypted media content for playback by and/or storage on the DVR 102.The media content may be protected by a DRM system in the serviceprovider's head-end and delivered to the DVR 102 in that format.Alternatively, the media content is delivered from the head-end using aconditional access (CA) system, which may be terminated by the DVR andthe media content is securely protected by the DVR local DRM system bydecrypting the CA signal and encrypting the recording with a uniquecontent key generated by the DVR's DRM system.

The DRM requirements also often define limitations on the number oftimes that the media content may be copied, if at all. The DVR 102 isthus configured to perform one or more conventionalencryption/decryption operations on the media content to ensurecompliance with the DRM requirements.

The content sharing system 100 also includes a portable multimediadevice (PMD) 120, which is depicted as being in communication with theDVR 102. The PMD 120 may be any suitable apparatus capable of storageand playback of media content, such as, a hand-held computer, a laptopcomputer, a personal digital assistant (PDA), a mobile telephone, etc.The PMD 120 may support one or more DRM systems in order to store andplayback protected media content, as discussed in greater detail hereinbelow.

In addition, the PMD 120 may be placed into communication with the DVR102 through any suitable wired or wireless connection, such as, over auniversal serial bus (USB) connection, a Bluetooth, MoCA, WiFi, Ethernetconnection, etc., or through use of a removable device, such as an SDCard. In instances where the DVR 102 is connected to a network, such asa wired or wireless network, the PMD 120 may also communicate with theDVR 102 over the network.

The content sharing system 100 is further depicted as including a rightsmanager 130 configured to transform the media content from a DRM formatsuitable for the DVR 102 to a DRM format that is suitable for the PMD120. The DRM format suitable for the PMD 120 comprises a format thatcomplies with a digital rights management system of the PMD 120. Thus,by way of example, the suitable format may comprise a format thatoperates under the Windows™ Media DRM (WMDRM) system for portabledevices, otherwise known as “Janus” or its newer version PlayReady.Other known DRM systems include OMA DRM v1 and v2, Marlin, Apple'sFairPlay, Motorola's IPRM, etc. These DRM systems typically downloadcontent from the content server and request a license, which includesthe content key and the DRM rights, from the license server. Thismechanism does not work, however, when the content is downloaded fromthe DVR 102 instead of the content server especially if the content onthe DVR is protected by a DRM system that generated the content keylocally while recording live TV content; therefore the content and thecontent key is not known to the license server.

According to an embodiment, the rights manager 130 is an apparatus thatis external to the DVR 102, such as a dongle, that may be connected tothe DVR 102 through, for instance, a USB connection. According toanother embodiment, the rights manager 130 comprises circuitry withinthe DVR 102 and is thus integrated with the DVR 102. According to afurther embodiment, the rights manager 130 comprises software stored ina memory or other computer readable storage medium of the DVR or adevice external to the DVR that is executable by a computer processor.Thus, although the rights manager 130 has been depicted in FIG. 1 asbeing separate from and connected to the DVR 102, it should beunderstood that the rights manager 130 may be integrated with the DVR102 without departing from a scope of the content sharing system 100disclosed herein.

As further depicted in FIG. 1, the rights manager 130 includes a DVRinterface module 132, an optional DVR content key receiving module 133,an optional DVR format suitable content version decrypting module 135,an optional encryption/decryption module 134, an optional transcodingmodule 136, an optional communications module 137, and an optional PMDinterface module 138. The transcoding module 136 is considered optionalbecause in some instances, the media content to be communicated to thePMD 120 need not be transcoded. The encryption/decryption module 134 isconsidered optional because in some instances, the media content to becommunicated to the PMD 120 need not be re-encrypted. The communicationsmodule 137 is considered optional because in some instances, the rightsmanager 130 may communicate to the license server 140 through aninterface provided in the DVR 102. In other instances, the rightsmanager 130 may communicate directly to the license server 140 and maythus include the communications module 137. The PMD interface module 138is considered to be optional because in some instances, the rightsmanager 130 may communicate to the PMD 120 through the DVR 102. In otherinstances, the rights manager 130 may communicate directly to the PMD120 and may thus include the PMD interface module 138. In any event, asecure protocol may be employed for communications between the rightsmanager 130 and the DVR 102.

The modules 132-138 may comprise hardware modules, software modules, ora combination of hardware and software modules. Thus, one or more themodules 132-138 may comprise circuitry and/or software configured toperform various functions in the rights manager 130. The variousfunctions that the modules 132-138 are configured to perform arediscussed in detail herein below.

The content sharing system 100 further includes a license server 140,database 142, and a content server 150. Generally speaking, the licenseserver 140 may be a combination of the standard license serverassociated with the DRM system employed by the PMD 120 with an extensionfunctionality that is capable of securely communicating with the DVR102, preferably using the DRM system employed by the DVR 102, such as,for instance, the Motorola IPRM system. The license server 140 isdepicted as being in communication with the DVR 102, and optionally, incommunication with the PMD 120. Although not shown, the license server140 may be in communication with a plurality of DVR's 102 and PMDs 120.

The DVR 102 may be configured to communicate with the license server 140through any suitable connection, such as, through the communicationsnetwork 110, through an Internet connection, etc. The direct connectionbetween the PMD 120 and the license server 140 is considered to beoptional because the PMD may be configured to communicate with thelicense server 140 through the connection with the DVR 102. However, ininstances where the PMD 120 is configured to communicate directly withthe license server 140, the connection may be made through the Internet,over a cellular network, etc. In any event, a secure protocol may beemployed for communications between the rights manager 130/DVR 102 andthe license server 140.

Various manners in which the components of the content sharing system100 depicted in FIG. 1 operate with respect to each other to enableaccess to media content stored on the DVR 102 with the PMD 120 isdescribed with respect to the methods 200-500 depicted in FIGS. 2A-5.The methods 200-500 are described with respect to FIG. 1 by way ofexample and not of limitation. It will thus be apparent to one ofordinary skill in the art that the methods 200-500 may be performed withsystems other than the content sharing system 100 depicted in FIG. 1. Inaddition, it should be apparent to those of ordinary skill in the artthat the methods 200-500 represent generalized illustrations and thatother steps may be added or existing steps may be removed, modified orrearranged without departing from scopes of the methods 200-500.

With reference first to FIG. 2A, there is shown a flow diagram of amethod 200 for communicating media content stored on the DVR 102 to aDRM protected PMD 120, according to an embodiment. One or more of thesteps contained in the method 200 may be performed by the rights manager130. As discussed above, the rights manager 130 may comprise anapparatus that is separate from the DVR 102 and configured tocommunicate with the DVR 102, such as, a dongle through a USBconnection, or other device external to the DVR 102 configured to atleast perform the functions discussed below.

In an alternate embodiment, the rights manager 130 may be integratedinto the DVR 102. In this embodiment, the DVR 102 may include circuitryand/or software configured to perform the functions of the rightsmanager 130 discussed below. The circuitry and/or software may beembedded into the DVR 102 in various manners that may make it difficultor impossible to distinguish the circuitry and/or software from othercircuitry and/or software contained in the DVR 102. As such, althoughparticular reference is made below to the rights manager 130, it shouldbe understood that in various instances, the DVR 102 or other componentsof the DVR 102 may be configured to perform all of the functionsdiscussed below with respect to the rights manager 130.

At step 202, the rights manager 130 receives an instruction tocommunicate a particular media content item stored on the DVR 102 to thePMD 120. The rights manager 130 may receive the instruction from a userdirectly through a user-interface of the DVR 102, for instance, throughthe DVR interface module 132. In addition, or alternatively, the rightsmanager 130 may receive the instruction from a user interaction with thePMD 120, for instance, through the PMD interface module 138.

At step 204, the rights manager 130 communicates a request for aportable content key associated with a content identification (ID) ofthe stored media content item to the license server 140. The rightsmanager 130 may be configured to communicate to the license server 140either directly or via a connection between the DVR 102 and the licenseserver 140. Thus, for instance, the rights manager 130 may be equippedwith an optional communications module 137 for communicating with thelicense server 140 through any of the communication options discussedabove with respect to the DVR 102.

The content ID generally comprises a substantially unique identificationvalue assigned to the media content item. Thus, for instance, variousmedia content items stored on the DVR 102 will be assigned differentcontent IDs. The DVR 102 may utilize the content ID to be able todistinguish between the various media content stored on the DVR 102.

According to an embodiment, the DVR 102 is configured to generate thecontent ID of the media content item, for instance, when the mediacontent item is stored on the DVR 102 or when a request for the portablecontent key associated with a media content item is made. In instanceswhere the media content item is transcoded, the DVR 102 or the rightsmanager 130 may associate a new portable content ID with the transcodedmedia content item to clearly differentiate the original media contentitem from the one transcoded for use by the PMD 120. In this case, allcommunication to the license server 140 uses the portable content IDinstead of the DVR content ID. In another embodiment, another component,such as the content server 150 or the license server 140 may generatethe content ID.

In any regard, the license server 140 is configured to receive therequest from the rights manager 130 as discussed in greater detail withrespect to the method 300 depicted in FIG. 3. FIG. 3, more particularly,depicts a flow diagram of a method 300 of generating and communicating aportable content key, according to an embodiment. As such, the licenseserver 140 is configured to perform the method 300.

As shown in the method 300, the license server 140 receives a requestfor the portable content key from the rights manager 130 at step 302.The request includes the content ID of the media content item to becommunicated to the PMD 120. Typically, protected content is associatedwith DRM rights and constraints that also need to be communicated to theDRM system on the PMD 120 together with the portable content key. Theserights may be communicated to the license server 140 at this step. Thiscommunication may use a secure protocol, such that the DRM rights cannotbe illegally altered. The DVR's DRM security protocol may be used orother security protocols such as SSL or TLS may be utilized.

In addition, the DVR content key generally comprises a key that isrelated to enabling the media content stored on the DVR to be translatedinto a format that is suitable for the PMD 120. In other words, the DVRcontent key enables the media content to be converted into a format thatcomplies with the digital rights management system of the PMD 120 bydecrypting the original content using the DVR content key before thecontent is optionally transcoded at step 212 and further re-encryptedusing the portable content key at step 214. By way of particularexample, the portable content key may enable the media content item tocomply with the Windows™ Media DRM for portable devices protocol.

At step 304, the license server 140 generates the portable content keyassociated with the content ID of the media content item. The licenseserver 140 may generate the portable content key through implementationof any suitable key generation operation. In one embodiment, the licenseserver 140 is configured to generate the portable content key throughimplementation of a deterministic operation based upon the content ID.

According to an embodiment, the license server 140 communicates theportable content key to the rights manager 130, as indicated at step310. In this embodiment, the license server 140 may discard the portablecontent key following communication of the portable content key to theDVR 102 or the rights manager 130. The license server 140 may discardthe portable content key in instances where the license server 140generates the portable content key deterministically from the content IDbecause the license server 140 may generate the same portable contentkey from the same content ID when a request for the portable content keyis received at a later time.

According to another embodiment, at step 306, the license server 140 maystore the portable content key in the database 142, for instance, toenable the license server 140 to be able to retrieve the portablecontent key when the license server 140 receives another request for theportable content key associated with the same particular content ID.This is particularly important when the DVR media content item isassociated with DRM rules that must be stored by the license server whenit communicates the portable content key to the PMD at step 406. Inaddition, or alternatively, the license server 140 may encrypt theportable content key at step 308 prior to communicating the portablecontent key to the rights manager 130. As such, in this embodiment, thelicense server 140 communicates the encrypted portable content key tothe rights manager 130 at step 310, for instance, using the samesecurity protocol as at step 302.

In the embodiment in which the license server 140 stores the portablecontent key, the license server 140 may be configured to automaticallydelete the stored portable content key in response to receipt ofinformation from the PMD 120 at step 510. This may not be desirable ifmultiple PMDs 120 owned by the user will receive the DVR media contentand may be requesting the same portable content key from the licenseserver 140. Alternatively, when the media content associated with theportable content key is deleted from the DVR 102, the DVR 102 may beconfigured to communicate this information to the license server 140.The license server 140 may then be configured to delete the storedportable content key since this key will no longer be required.

With reference back to FIG. 2, at step 206, the rights manager 130receives the portable content key from the license server 140. Therights manager 130 may also store the portable content key in a memory(not shown). At step 208, the rights manager 130 receives the DVRcontent key from the DVR 102. Alternatively, the rights manager 130 mayhave received the DVR content key from the DVR 102 at step 202. Inaddition, at step 210, the rights manager 130 may receive the mediacontent item from the DVR 102 and may decrypt the media content itemusing the DVR content key.

At step 212, the transcoding module 136 of the rights manager 130optionally transcodes the media content to a format suitable for the PMD120, which also includes a format that complies with one or more DRMsystems supported by the PMD 120. A suitable format includes, forinstance, the Windows™ Media DRM for portable devices. In addition, atstep 214, the encryption/decryption module 134 of the rights manager 130encrypts the PMD format suitable content using the portable content key.According to an embodiment, steps 210-214 may be executed in a loop suchthat the media content is decrypted, transcoded and re-encrypted insmall increments (e.g. packets, frames, video access units, etc.). Ifthe DRM system on the DVR 102 and the DRM system on the PMD 120 use thesame media content format and encryption algorithm, the transcoding step212 and the re-encryption step 214 may be omitted. In addition, steps208 and 210 may also be considered to be optional in this case.

At step 216, the encrypted content is communicated to the PMD 120through either a direct connection between the rights manager 130 andthe PMD 120 or through a connection between the DVR 102 and the PMD 120or through a removable media, such as an SD card.

Turning now to FIG. 2B, there is shown a flow diagram of a method 250for communicating media content stored on the DVR 102 to a DRM protectedPMD 120, according to another embodiment. In this embodiment, theportable content key is generated in the DVR 102 instead of by thelicense server 140. In addition, similarly to the method 200, one ormore of the steps contained in the method 250 may be performed by therights manager 130.

At step 202, the DVR 102 receives an instruction to communicate aparticular media content item stored on the DVR 102 to the PMD 120 asdiscussed above with respect to the method 200. In addition, at step252, a portable content key is generated by the DVR 102 instead of thelicense server 140.

At step 254, the DVR 102 communicates the portable content key to thelicense server 140 and the license server 140 stores the portablecontent key as indicated at step 256. Although not explicitly stated,the license server 140 may also receive and store the DRM rulesassociated with the media content at step 256. This communication of theportable content key, portable content id and the DRM rules may be donethrough a secure protocol similar to step 308.

In addition, steps 212-216 as discussed above with respect to the method200 may be performed in the method 250.

Turning now to FIG. 4, there is shown a flow diagram of a method 400 ofenabling media content from the DVR 102 to be accessed in the PMD 120.As such, the PMD 120 is configured to perform the method 400.

At step 402, the PMD 120 receives the encrypted content from the rightsmanager 130. The PMD 120 also receives the portable content ID of themedia content item. The content ID may be optionally stored in thecontent file itself, such as in the file header. At this point, the PMD120 is unable to access the encrypted PMD format suitable contentbecause the PMD 120 does not have the appropriate key to decrypt theencrypted PMD format suitable content.

At step 404, the PMD 120 communicates a request for a portable contentkey from the license server 140, which includes the content ID. Again,as discussed above, the PMD 120 may communicate directly to the licenseserver 140 or via the connection between the DVR 102/rights manager 130and the license server 140. The portable content key generally comprisesa key that is related to enabling the decryption of a media content itemthat the rights manager 130 has encrypted to be into a format thatcomplies with the digital rights management system of the PMD 120. Byway of particular example, the PMD 120 executes typical Windows™ MediaDRM (WMDRM) transactions to obtain the content key and the associatedDRM rules in the form of a WMDRM license request from the PMD 120 andWMDRM license response from the license server 140; the portable contentkey may enable the media content to be decrypted such that it complieswith the WMDRM for portable devices. Another example may include aRights Object request from the PMD 120 to the Rights Issuer to receive aRights Object with the content key and the DRM rules compliant with theOMA DRM specification.

In any regard, the license server 140 is configured to receive therequest from the PMD 120 as discussed in greater detail with respect tothe method 500 depicted in FIG. 5. FIG. 5 depicts a method of generatingand communicating a portable content key, according to an embodiment. Assuch, the license server 140 is configured to perform the method 500.

As shown in the method 500, the license server 140 receives a requestfor the portable content key from the PMD 120 at step 502. The requestincludes the content ID of the media content communicated to the PMD120.

At step 504, the license server 140 generates the portable content keyassociated with the content ID of the media content item. The licenseserver 140 may generate the portable content key through implementationof any suitable key generation operation. In one embodiment, the licenseserver 140 is configured to generate the portable content key throughimplementation of a deterministic operation based upon the content ID.

According to an embodiment, the license server 140 communicates theportable content key to the PMD 120, as indicated at step 510. In thisembodiment, the license server 140 may discard the portable content keyfollowing communication of the portable content key to the PMD 120. Thelicense server 140 may discard the portable content key in instanceswhere the license server 140 generates the portable content keydeterministically from the content ID because the license server 140 maygenerate the same portable content key from the same content ID when arequest for the portable content key is received at a later time.

According to another embodiment that corresponds to the method 250depicted in FIG. 2B, step 504 may be replaced by step 506, where thelicense server 140 retrieves the portable content key from the database142 when the license server 140 receives a request for the portablecontent key associated with a particular content ID. In this embodiment,the portable content key received from the DVR 102 was stored by thelicense server 140 at step 256. In addition, the license server 140encrypts the portable content key at step 508 prior to communicating theportable content key to the PMD 120. As such, at step 510, the licenseserver 140 communicates the encrypted portable content key to the PMD120 using the standard mechanism of the PMD's 120 DRM system.

With reference back to FIG. 4, at step 406, the PMD 120 receives theportable content key from the license server 140. At step 408, the PMD120 decrypts the portable content key according to the PMD's 120 DRMsystem. In addition, at step 410, the PMD 120 decrypts the encrypted PMDformat suitable content with the portable content key to thereby accessthe PMD format suitable content. If DRM rules were received with theportable content key, the PMD's 120 DRM system may enforce those rulesbefore decrypting the content key and the content item in steps 408 and410, respectively.

Through implementation of the methods 200-500, media content stored onthe DVR 102 may be communicated to and played by the PMD 120. Moreparticularly, the PMD 120 is able to access and play the media contentbecause the media content is transcoded to a suitable format forplayback on the PMD 120. In addition, the communication of thetranscoded content is secure because the PMD 120 is unable to access thetranscoded content without receiving the appropriate portable contentkey from the license server 140. In one particular regard, the PMD's 120DRM system may be used with no modification or extensions to obtain theportable content key for the content originating from the DVR 102instead of the more traditional way of receiving content from thecontent server 150.

Some or all of the operations set forth in the methods 200-500 may becontained as a utility, program, or subprogram, in one or more desiredcomputer readable storage media. In addition, the methods 200-500 may beembodied by one or more computer programs, which can exist in a varietyof forms both active and inactive. For example, they may exist assoftware program(s) comprised of program instructions in source code,object code, executable code or other formats. Any of the above may beembodied on one or more computer readable storage media, which includestorage devices.

Exemplary computer readable storage media include conventional computersystem RAM, ROM, EPROM, EEPROM, and magnetic or optical disks or tapes.Concrete examples of the foregoing include distribution of the programson a CD ROM or via Internet download. It is therefore to be understoodthat any electronic device capable of executing the above-describedfunctions may perform those functions enumerated above.

FIG. 6 illustrates a block diagram of a computing apparatus 600configured to implement or execute one or more of the methods 200-500depicted in FIGS. 2A-5, according to an embodiment. It should beunderstood that the illustration of the computing apparatus 600 is ageneralized illustration and that the computing apparatus 600 mayinclude additional components and that some of the components describedmay be removed and/or modified without departing from a scope of thecomputing apparatus 600.

The computing apparatus 600 includes a processor 602 that may implementor execute some or all of the steps described in one or more of themethods 200-500. Commands and data from the processor 602 arecommunicated over a communication bus 604. The computing apparatus 600also includes a main memory 606, such as a random access memory (RAM),where the program code for the processor 602, may be executed duringruntime, and a secondary memory 608. The secondary memory 608 includes,for example, one or more hard disk drives 610 and/or a removable storagedrive 612, representing a floppy diskette drive, a magnetic tape drive,a compact disk drive, etc., where a copy of the program code for one ormore of the methods 200-500 may be stored.

The removable storage drive 610 reads from and/or writes to a removablestorage unit 614 in a well-known manner. User input and output devicesmay include a keyboard 616, a mouse 618, and a display 620. A displayadaptor 622 may interface with the communication bus 604 and the display620 and may receive display data from the processor 602 and convert thedisplay data into display commands for the display 620. In addition, theprocessor(s) 602 may communicate over a network, for instance, theInternet, LAN, etc., through a network adaptor 624.

It will be apparent to one of ordinary skill in the art that other knownelectronic components may be added or substituted in the computingapparatus 600. It should also be apparent that one or more of thecomponents depicted in FIG. 6 may be optional (for instance, user inputdevices, secondary memory, etc.).

While the embodiments have been described with reference to examples,those skilled in the art will be able to make various modifications tothe described embodiments without departing from the true spirit andscope. The terms and descriptions used herein are set forth by way ofillustration only and are not meant as limitations. In particular,although the methods have been described by examples, steps of themethods may be performed in different orders than illustrated orsimultaneously. Those skilled in the art will recognize that these andother variations are possible within the spirit and scope as defined inthe following claims and their equivalents.

1. A method for communicating media content stored on a digital videorecorder (DVR) protected by a first digital rights management (DRM)system to a portable multimedia device (PMD) using a second DRM system,wherein the first DRM system differs from said second DRM system, saidmethod comprising using one or more processors to perform steps of: (a)receiving a request for communication of a media content item stored onthe DVR to the PMD; (b) employing a portable content key to encrypt themedia content item to a PMD format suitable content version; and (c)communicating the encrypted PMD format suitable content version to thePMD along with a portable content identifier (ID), wherein the portablecontent ID comprises a unique identification value assigned to the mediacontent item.
 2. The method according to claim 1, further comprisingusing the one or more processors to perform steps of: communicating arequest for the portable content key associated with a portable contentID of the stored media content item to a license server; and receivingthe portable content key associated with the portable content ID fromthe license server prior to step (b).
 3. The method according to claim2, further comprising: employing a secure protocol for one or both ofcommunicating the request for the portable content key and receiving theportable content key.
 4. The method according to claim 2, furthercomprising: in the license server, generating the portable content keyin response to receipt of the request for the portable content keyassociated with the content ID of the media content item; andcommunicating the portable content key to the DVR.
 5. The methodaccording to claim 4, further comprising: storing the generated portablecontent key in a database.
 6. The method according to claim 2, furthercomprising: receiving DRM rules associated with the media content itemfrom the DVR and storing the DRM rules associated with the media contentitem.
 7. The method according to claim 5, further comprising:determining that the media content item has been deleted from the DVR;communicating an indication to the license sever that the media contentitem has been deleted from the DVR; and in the license server, deletingthe portable content key from the database.
 8. The method according toclaim 4, further comprising: in the license server, encrypting theportable content key; and wherein communicating the portable content keyfurther comprises communicating the encrypted portable content key; andwherein receiving the portable content key further comprises receivingthe encrypted portable content key, said method further comprising:decrypting the encrypted portable content key prior to step (b).
 9. Themethod according to claim 1, further comprising: generating the portablecontent key in the DVR prior to step (b); and communicating the portablecontent key to a license server, wherein the license server isconfigured to store the portable content key.
 10. The method accordingto claim 1, wherein the media content item stored on the DVR isencrypted, said method further comprising: receiving a DVR content key;and decrypting the media content item using the DVR content key prior tostep (b).
 11. The method according to claim 1, wherein one or more ofsteps (a)-(c) are performed by a rights manager.
 12. The methodaccording to claim 11, wherein the rights manager comprises an apparatusthat is separable from the DVR.
 13. A rights manager for transforming amedia content from a first digital rights management (DRM) formatsuitable for a digital video recorder (DVR) to a second DRM formatsuitable for a portable multimedia device (PMD), said rights managercomprising a processor, wherein the processor further comprises: amodule for receiving a media content identification (ID) of the mediacontent stored on the DVR; a module for receiving a DVR content key ofthe media content stored on the DVR; a module for decrypting the DVRformat suitable content version of a media content item using a DVRcontent key; a module for encrypting a PMD format suitable contentversion of a media content item using a portable content key; and amodule for communicating the encrypted PMD format suitable contentversion to the PMD along with a portable content identifier (ID),wherein the portable content ID comprises a unique identification valueassigned to the media content item.
 14. The rights manager according toclaim 13, wherein the processor further comprises: a module forinterfacing directly with the PMD.
 15. The rights manager according toclaim 13, wherein the rights manager is an apparatus that is separateand distinct from the DVR.
 16. The rights manager according to claim 13,wherein the rights manager is integrated into the DVR.
 17. Anon-transitory computer readable storage medium on which is embedded oneor more computer programs, said one or more computer programsimplementing a method for communicating media content stored on adigital video recorder (DVR) protected by a first DRM system to aportable multimedia device (PMD) using a second DRM system, wherein thefirst DRM system differs from said second DRM system, said one or morecomputer programs comprising a set of instructions for: (a) receiving arequest for communication of a media content item stored on the DVR tothe PMD; (b) employing a portable content key to encrypt the mediacontent item to a PMD format suitable content version; and (c)communicating the encrypted PMD format suitable content version to thePMD along with a portable content identifier (ID), wherein the portablecontent ID comprises a unique identification value assigned to the mediacontent item.
 18. The non-transitory computer readable storage mediumaccording to claim 17, said one or more computer programs furtherincluding a set of instructions for: generating the portable content keyin one of the DVR and the license server.
 19. The non-transitorycomputer readable storage medium according to claim 17, said one or morecomputer programs further including a set of instructions for:communicating a request for the portable content key associated with acontent identification (ID) of the stored media content to a licenseserver; and receiving the portable content key associated with thecontent ID from the license sever prior to step (b).
 20. Thenon-transitory computer readable storage medium according to claim 19,said one or more computer programs further including a set ofinstructions for: employing a secure protocol in communicating therequest for the portable content key to the license server.